Commercial aircraft typically include air machines such as ram air fans, air cycle machines, and cabin air compressors. The air machines utilize rotating shafts to drive the air machine by imparting a rotation of the shaft onto a portion of the components in the air machine. In order to support and guide the rotating shaft, journal bearings are placed on the shaft and connected to the air machine.
A typical journal bearing includes a cylindrical sleeve that fits around the shaft and is axially aligned with the shaft. Between the sleeve and the shaft is a fluid, such as air or another lubricant. The fluid creates a minimal friction rotating environment for the shaft.